The present proposal seeks funds to conduct a new cycle of research on the sociospatial structure of standard metropolitan statistical areas (SMSAs) in the United States, using the data for census tracts now available from the 1980 census and the methodological and research accomplishments achieved under a previous grant (PHS 1 RO1 HD 12865-01A1, "The Changing Sociospatial Structure of the City.") For purposes of this research, "sociospatial structure" is measured in five ways: (a) Ecological Community Area (ECA) classification-combinations of similar census tracts, analogous to the nucleation theories of Chauncey Harris. b) Distance and direction from the Central Business District (CBD), permitting testing of zonal and sector theories of Ernest Burgess and Homer Hoyt, respectively. c) Housing types, condition, and amenities, testing theories of residence as a compromise between consumer adjustment and location with respect to work, after the writings of Peter Rossi. d) Livelihood base-the sources from which livelihood (income) is gained, the occupations pursued to gain it, following the theories of urban economists. e) Neighborhood characteristics (race, ethnicity, educational attainment, type of families) responsive to a more sociological orientation. It is proposed to use these dimensions to study four research topics widely recognized to be of both scientific and practical significance in understanding the modern metropolis and its problem: 1. The sociospatial pattern of population composition. 2. The sociospatial pattern of fertility differentials. 3) The sociospatial pattern of marital status, households, and families. 4. The sociospatial pattern of problems associated with children and youth. The research will be both comparative-performing the research for a sample of SMSAs-and longitudinal-comparing the findings for different census dates, especially for the 1970-1980 decade.